The present invention relates to a safety device for blood-, wound secretion- or infusion supplying conduit which leads to a vessel inlet and blood-, wound secretion or infusion supply system provided therewith.
Safety devices of the above mentioned general type are known in the art. One of such safety devices on an infusion hose is disclosed in the German document DE 33 44 817 C2. In this device a photoelectric drop detecting device is arranged on a drop chamber, and a control device with a mechanical regulating arrangement acts on immovable lever for regulating the infusate flow by squeezing the infusion hose against an abutment. For providing a dynamically controllable, mechanical safety device for suddenly interrupting the infusate flow in the event of disturbances in the mechanical or electronic systems without indicating a current supply, it is proposed in this document to use as the safety device a rocker- or plunger-shaped actuating element which is prestressed by a spring and acts on the lever. A current excited holding magnet which counteracts the spring force holds the actuating element in an open ready position, and in the event of a drop of the magnet current brings the movable lever into a position in which it completely squeezes the infusion hose and thereby brings the infusate flow to sudden interruption. The whole safety device provides the interruption of the life sustaining infusion to the patients when certain disturbances occur. Thereby however a patient is not serviced. This safety device does not take into consideration disturbances of the infusate flow, which are caused for example by patients themselves when an infusion canula is completely or partially pulled out or pressed in. In this case the known infusion regulating apparatus adjusts the infusate flow to the changing conditions by corresponding nominal-actual value comparison, without triggering an alarm. Moreover, this known infusion regulating apparatus and its safety device must have a complicated construction which is also susceptible to corresponding disturbances.
U.S. Pat. No. 4,747,832 discloses an infusion apparatus with mechanical parts implanted under the skin of a patient and with expensive electronic parts arranged outside of the skin for infusion of intramuscular or intravenous medicaments, for example, insulin for treatment of diabetes, neuroleptic, zytostatics or other medicaments. The control of the liquid to be infused from the container is performed by magnetic elements which are arranged at both sides of the skin and set in operation from outside by a crank or an electric regulator for supplying the required infusion liquid from the supply container by an infusion pump through several regulating valves to an output of a catheter. The operation of the infusion pump is based on the law that the total infusion quantity supplied by it is equal to the sum of the partial quantity from the supply container and a further partial quantity in the catheter to be constant. However, the non-uniformities which are produced by a position displacement of the catheter or the supply conduit are not taken into consideration and do not trigger an alarm, due to displacement of the catheter. Moreover, this apparatus is always connected with an implantation of its mechanical parts, and in view of its complicated construction involving a plurality of differently designed, multi-stage gears should be considered as disturbance-prone.
An efficient safety device of the above mentioned type has not been developed yet for a long time.
In order to provide some help in this situation, the conduit which leads to or from is glued with adhesive tapes, or in the case of central vein catheters it is sewn. However, no direct technical monitoring system is provided. Therefore, displacement of canulas or catheters, which as a rule is not recognized can lead to substantial risks to the patient, such as follows:
Air embolism in case of central vein catheters; PA1 Blood loss during transfusions or blood return; PA1 Contamination of the vessel input.
Several examples for the above mentioned three main groups of risks are presented hereinbelow.
As for the air embolism in the case of central vein catheters, in the case of coincidence of a negative central vane pressure and a partial displacement of a central vein catheter an air embolism occurs. During air embolism the air is drawn into the circulation of the patient, it causes a displacement of the capillary regions in heart or lungs and can lead to death.
As for the blood losses, the conventional dialysis apparatuses measure the resistance between the apparatus and the patient during a return of the blood. The blood is supplied with a speed of 200-400 ml/min through a canula into the patient. The resistance of the canula constitutes a great part in the pressure monitoring region of the dialysis apparatus. In the event of displacement of the canula, the blood flows from the arterial vessel input and the dialysis apparatus outwardly of the patient. The dialysis apparatus reacts first due to secondary influences.
Finally, as for the contamination of the vessel input, the blood-, wound secretion- and infusion supplying vessel inlets can slide out. Hygienically microbial impurities can be located on these unprotected vessel inputs.